One example of a known switched communications network is the public switched telephone network ("PSTN"). In that network, individual subscriber lines are connected to a local end office switch that is capable of connecting one subscriber to another subscriber or to a trunk line that connects to another switch.
Tandem switches ("tandems") are switching systems that switch between switching systems, such as end offices or other tandems. Local tandems provide connections between end offices for local calls in the same Local Access and Transport Areas ("LATAs"). Direct trunk lines also provide connections between switching systems, and in particular may provide connections between two end offices in the same LATA.
Access tandems provide entry points into a LATA for an interexchange provider ("IXP"). An IXP is any carrier which is authorized to provide service on an interLATA basis (i.e., a "toll call"). Two access tandems and an IXP provide a connection between two end offices for toll calls in different LATAs. At least one access tandem is used to obtain access to IXP services and at least two access tandems are used to provide interLATA connections.
In order for the switching network to properly place a call (i.e., establish a communication path between two subscribers), that call must contain a call code, including an origination code and a destination code. As used herein, the term "code" refers to one or more signals for conveying information originating in a first location and destined for a second location, that contain voice or data content to be transferred from the first location to the second location, and optionally data that control how the voice or data content is transferred. An origination code usually includes the identification number of the caller ("caller ID"). As used herein, an abbreviated code is any code that must be translated in order for a switch or server to properly handle that call. The caller ID may be used locally by a Local Exchange Carrier or an IXP for (1) routing the call to a selected IXP, (2) connecting to one or more desired services, such as voice mail and other enhanced information services on the switched network, and (3) billing the caller. A destination code usually includes the identification number of the called subscriber. The call code may also include other additional information such as control information that may provide auxiliary functions, such as restricting a call from being placed to certain destinations.
Common protocols used to convey call codes include dial pulsing (i.e., for use with a rotatory telephone), dual-tone multi frequency ("DTMF") pulsing (i.e., for use with push-button phones), and multi frequency pulsing (i.e., for use with trunk lines).
A disadvantage of conventional methods for providing access to network services is that the requesting subscriber is inconvenienced by the relatively large number of digits required to place one or more calls. Therefore, it would be desirable to provide a method for providing network services on a switched communications network that expedites switching between network services provided by the same or different IXPs.
Another disadvantage of conventional methods for providing access to network services is that access to those services is not rapid, particularly to enhanced services. Enhanced services are services which may be provided to a subscriber without the normally expensive high bandwidth connections that are usually required for real-time voice transmission. For example, when a subscriber wishes to switch between different network services, that subscriber may be required to hang-up and redial the entire new destination code, especially when the desired new service is provided by a different IXP. Redialing is slow, inconvenient to the caller, and wastes valuable access tandem resources because it requires that the caller terminate and reinitiate communication paths between the caller and the IXP for each subsequent call. Therefore, it would be desirable to provide expedited services to subscribers who wish to switch between network services on any particular IXP.